The present invention relates to a cylinder head sealing structure, and more particularly to a cylinder liner collar sealing structure for piston engines.
In known engine designs, such as shown in U.S. Pat. No. 3,481,316 or U.S. Pat. No. 3,363,608, a cylinder liner has an annular flange or collar at its upper end. This collar has a sealing surface which faces towards the cylinder head. An annular head gasket or fire ring is mounted between the collar and the cylinder head. Combustion pressures will tend to radially expand the head gasket during operation of the engine. The cylinder head to liner joint is one of the most critical areas of a Diesel engine. High temperature gasses at pressures frequently exceeding 2000 psi must be sealed under cyclic conditions. The head gasket must be compliant enough to seal surface imperfections, yet be stiff enough not to relax to the point where insufficient clamping load causes gasket blowout. To avoid such blowout, it is known in the prior art to clamp the liner collar between the cylinder head and a cylinder jacket. A disadvantage of such an arrangement is that the clamping forces will bend the collar so that its outer edge will be farther from the cylinder head than its inner edge. Such a condition increases the chances of sealing failure. Another disadvantage of such an arrangement is that considerable alternating forces caused by the forces occurring within the cylinder are transmitted to the collar to which have to be added the clamping forces. The result is the occurrence at the cylinder liner collar of considerable bending moments which one seeks to maintain small as possible by a corresponding dimensioning and arrangement of the clamping surfaces at the collar and at the abutment shoulders of the cylinder jacket.